A “super-hydrophobic” surface or particle is generally defined and is defined herein as that which has a contact angle greater than 150 degrees with a drop of water. Superhydrophobic (SH) coatings have been under development for many years. A major reason why superhydrophobic coatings have not been widely commercialized is due to their inherent lack of durability. This lack of durability is caused by the superhydrophobic particles themselves, in that these particles not only repel water, but also generally repel binders that could be used to attach them to various surfaces. Therefore, in order to overcome the repulsive forces of the binders a significant amount of binder often needs to be added. A problem arises, however, because in some cases the amount of binder required to find the superhydrophobic particles destroys the superhydrophobic behavior of the coding by feeling the nanoscale surface topology required to allow the superhydrophobic particles to be superhydrophobic.
Additionally, superhydrophobic coatings are typically only superhydrophobic at the coating's outer surface. Once the outer surface is abraded away, the surface is no longer superhydrophobic. This loss of superhydrophobicity is due to the superhydrophobic particles or structure being removed from the surface. Particles that are beneath the surface generally have their nanopores and nanotextured surfaces clogged with the underlying coating material, typically rendering them non-superhydrophobic.
In a standard electrostatic powder spraying process, dry resin powder, is electrostatically sprayed onto a given electrically grounded substrate. The electrically charged dry powder adheres to the grounded substrate by electrostatic forces. When the dry resin powder is cured, it becomes well bonded to the substrate.
A durable superhydrophobic coating capable of rendering a surface superhydrophobic would be extremely valuable. The applications of such surfaces are nearly endless. For example, a superhydrophobic car windshield would be virtually impervious to rainwater; and a superhydrophobic boat hull would minimize friction between the hull and the water. Therefore, a need exists to secure superhydrophobic particles to various surfaces such that the resulting coating is durable and retains its superhydrophobic characteristics.